Monitoring systems and devices for monitoring breathing activity of human subjects and especially for apnea detection of babies, typically monitor a breathing pattern of the subject and operate an alarm mechanism in case breathing irregularity is detected.
Some systems for monitoring baby breathing use movement sensing for identification of breathing of the subject. These systems include one or more sensor-platforms placed underneath the baby's mattress to monitor his/her breathing related movements while the baby is asleep, and one or more control devices that usually hang over the subject's bed. These platforms usually include a lower plate and a covering upper plate, where a piezoelectric sensor and a flexible mediating element such as a rubber/elastomeric element are positioned there-between. The mediating element mediates between the upper plate and piezoelectric sensor to avoid erosion of the surface of the sensor and soften the impact upon the piezoelectric sensor surface, which can lose its sensitivity if not maintained in that way.
The rubber element receives the movements of the subject applied upon the upper plate and transmits them to the piezoelectric transducer, which in turn converts the mechanical force applied thereon into a corresponding electric signal. The rubber element is typically attached to the inner side of the upper plate such that it will interface the piezoelectric surface (which is attached to the inner side of the lower plate) at the center of the sensor's surface to allow maximal transmission of mechanical force to be received by the piezoelectric surface.